Medical image scanners like x-ray, computerized tomography (CT), cone beam computerized tomography (CBCT), magnetic resonance imaging (MRI), positron emission tomography (PET), or ultrasound typically acquire raw intensity values in a very high dynamic range. For instance, several commercially available computed tomography scanners are able to cover a range of about 4,000 different intensities. This high dynamic range is usually too large to fit most display devices. It is practical, therefore, to map the high dynamic range to a smaller intensity interval, such as the 256 different gray-scale values of a typical computer monitor. This can be accomplished by choosing a continuous range of interest out of the full input intensity range by setting two parameters: the width of the range, also referred to as “window,” and the center of the range, also referred to as “level.” For displaying an image, all input intensities within that range are then continuously mapped to the full range of output intensities. Input intensities below and above that range are mapped to the minimal and maximal output intensities. This mapping technique is not only employed to address the above-mentioned described technical limitations of display devices but also factors in that the human eye is not sufficiently sensitive to differentiate between all input intensities. Choosing a small intensity window allows for enhancing image contrast in a specific range of interest while masking out all other intensities that may not contain relevant information. The output from the described mapping technique is not constrained to gray scale values. The intensity window can also establish a mapping between the input values and a user-defined color map.
Several different approaches are possible in selecting suitable window and level parameters. Various algorithms have been developed for determining those values automatically based on image content, display properties, and a desired case. However, most display systems additionally include tools for setting those values manually, e.g. by entering numbers or by moving sliders, for situations where an automatic algorithm is not able to produce the target result.
Accordingly, it is desirable to have a system and method for simplifying the manual window/level adjustments in the simultaneous display of two or more images for medical image applications and instrumentations.